The documents said the NSA's hacking into the Qatar-based Al Jazeera's networks was a feat considered "particularly successful," reports Der Spiegel, a German publication that viewed the material.

Al Jazeera, which recently began broadcasts on United States' cable and satellite networks, frequently broadcast audio and video messages from al-Qaida leaders for nearly 10 years.

A document dated March 23, 2006, said the NSA was able to read communications by the "interesting targets" that were being specifically protected by Al Jazeera. NSA officials, though, were not satisified with Al Jazeera's analysis of languages, reports Der Spiegel.

Accessing "Al Jazeera broadcasting internal communication" was called a "notable success," according to the document, and the targets found "had high potential as sources of intelligence."

The information was forwarded for further analysis, said the document. It did not specify how much the NSA spied on Al Jazeera's journalists or management.

Al Jazeera has not issued comment about the suspected breach. The media network, though, has been hacked in the past by the Syrian Electronic Army, not the NSA,reports Venture Beat. That breach, in 2012, was done to deface a live blog being run about the ongoing Syrian conflict.

Snowden, 30, remains in Russia, where President Vladimir Putin allowed him to stay on a temporary asylum visa rather than return to the United States to answer charges filed after he leaked top-secret documents to publications around the world.